其法分东、西、南、北为四正，又分东南、西南、东北、西北为四维，合计为八方，各
有主气，南风热、东风温、西风燥、北风寒，东南风温而热、西南风燥而热、东北风寒而温
、西北风寒而燥，此其平也，太过者则贼风矣。贼风轻，其中于人也，亦轻；贼风重，其中
于人
八方之温热寒燥，只以东西南北辨之，不论四时皆有，与六气之春温、夏热、秋燥、冬
寒各主一时者不同也。
卫气温养形体，《内经》所谓卫外而为固，《难经》所谓守邪之神也。卫气固密，则百
邪不能侵，若少有罅隙，则邪即袭之矣。其隙在头，则中于面，但为口眼 而已，其手足
固无恙也。其隙在手经，则中于臂，但为腕臂不举而已，其头足固无恙也。其隙在足经，
则中于髀枢，但为步履迟重而已，其头手固无恙也。其隙在左，则中左而右无恙；其隙在
右，则中右而左无恙。中足少阴，则舌枯而语言蹇涩（少阴之脉上萦舌本）；中手厥阴，则
神倦而多健忘（手厥阴心主本代心君行事也）；中手少阳，则三焦不利而多噎气，且大便不
行；中足太阳，则膀胱不清而多溲浊，甚至小便癃闭而不能出，以膀胱气化全凭卫气渗利，
卫气为邪风所袭，不能渗利，故癃闭也。种种诸症，难以枚举，总各视其隙之所在耳。《内经
》曰∶邪之所凑，其正必虚。以比斫材，木坚者不入，脆者皮弛，正谓此也。是以此症多发于
中年以后之人，以其卫气不无少衰也。若少壮之人，则百中无一，以其卫气正盛也。后人不明
卫气之义，乃有左血右气之说，失之远矣。又有谓血虚生内风者，亦不甚切，殊不知内风之生
，乃卫气之虚而有隙，如谷虚则生风耳。非血虚也。虚则有隙，而邪风入之，故曰内风感召外
风也。卫气出于下焦，为生风之根，即《内经》所谓肾间动气也。其开合寤寐出入间，皆以足
少
亦左右分布。凡人之始，初结胎时，其形如两甲，即两肾也，而卫气寓焉，故其开合寤寐出
入间，行亦必左右分布，此内景之确而可信者，特粗工不能识耳。
动气之根，即是肾气，然必曰肾间动气者，以其为知觉运动之主，故加一动字以称之。
若两边卫气平均，则知觉运动自然爽健精明。若一边卫气无病，一边卫气有病，则知觉运动必不
能如平日之爽健精明矣。语云∶众擎易举，独力难胜。可以为譬。
风中于左，则病在左；中于右，则病在右。独口角之 斜则不然，中左者，口必 右；
中右者，口必 左。所以然者，左则左边卫气不用，而经脉弛缓不收，右边卫气独用，而经脉牵
引拘急，故必 右（口角经脉是阳明经环于唇口者，左右各一）。其中右者仿此。
这种分类方法将东、西、南、北四个正方向作为四正，又将东南、西南、东北、西北四个斜向作为四维，合计为八方。每一方都有对应的主气：南风主热，东风主温，西风主燥，北风主寒；东南风兼具温与热，西南风兼具燥与热，东北风兼具寒与温，西北风兼具寒与燥。这是正常的气候状态（平气），如果风气太过，就称为贼风。贼风轻微，人受邪也轻；贼风严重，人受邪也重。
八方之风的温、热、寒、燥，仅以东西南北方位来辨别，不论四季何时都有，这与六气（风、寒、暑、湿、燥、火）中春温、夏热、秋燥、冬寒各主一季的情况不同。
卫气具有温养形体的作用，《黄帝内经》称之为“卫外而为固”，《难经》称之为“守邪之神”。卫气坚固致密，则各种邪气不能侵入；如果稍有缝隙，邪气就会乘袭而入。如果缝隙在头部，邪气中于面部，只表现为口眼歪斜，而手足安然无恙。如果缝隙在手部经脉，邪气中于手臂，只表现为手腕和手臂不能抬起，而头足安然无恙。如果缝隙在足部经脉，邪气中于大腿关节，只表现为步履迟缓沉重，而头手安然无恙。如果缝隙在左侧，则病在左侧而右侧无恙；如果缝隙在右侧，则病在右侧而左侧无恙。
如果邪气中于足少阴肾经，则舌体干枯且语言蹇涩（因为少阴经脉上绕舌根）；如果邪气中于手厥阴心包经，则神志疲倦且多健忘（因为手厥阴心包代心君行事）；如果邪气中于手少阳三焦经，则三焦功能不利而多噎气，并且大便不通；如果邪气中于足太阳膀胱经，则膀胱气化不清而小便浑浊，甚至出现小便癃闭（排尿困难或闭塞）而不能排出，这是因为膀胱的气化全赖卫气的渗利作用，卫气被邪风侵袭，不能发挥渗利作用，所以导致癃闭。种种症状，难以一一列举，总之都是根据邪气入侵的缝隙所在部位而定。《黄帝内经》说：“邪气聚集的地方，正气必然虚弱。”这好比砍伐木材，木质坚硬的斧头不易切入，木质脆软的则皮肉松弛，正是这个意思。因此，这类病症多发于中年以后的人，因为他们的卫气多少有些衰退。如果是年轻力壮的人，则百人中无一患病，因为他们的卫气正值旺盛。后人不明白卫气的含义，于是有了“左血右气”的说法，这就差得太远了。又有说是血虚产生内风的，也不甚确切，殊不知内风的产生，乃是卫气虚弱而有缝隙，就像山谷空虚则生风一样。并非血虚。因为有虚就有缝隙，邪风由此进入，所以称为内风感召外风。卫气出于下焦，是生风的根本，也就是《黄帝内经》所说的肾间动气。卫气的开合、寤寐（睡眠与觉醒）、出入之间，都左右分布。凡人的初始，刚结成胎时，其形状如两片甲壳，即两肾，而卫气寓居其中，所以它的开合寤寐出入运行，也必然是左右分布，这是内景（体内生理景象）确实可信的证据，只是粗劣的医生不能识别罢了。
肾间动气的根本，就是肾气，但之所以称为肾间动气，是因为它是知觉和运动的主宰，所以加一个“动”字来称呼它。如果两边的卫气平均，则知觉运动自然爽快健康、精明灵敏。如果一边卫气无病，另一边卫气有病，则知觉运动必然不能像平日那样爽快健康、精明灵敏了。俗话说：“众人抬举容易举起，单独用力难以胜任。”可以以此作比喻。
风邪中于左侧，则病在左侧；中于右侧，则病在右侧。唯独口角歪斜不是这样，中于左侧者，口角必歪向右侧；中于右侧者，口角必歪向左侧。之所以如此，是因为左侧卫气不用，导致左边经脉弛缓不收，而右边卫气独用，导致右边经脉牵引拘急，所以口角必歪向右侧（口角部的经脉是阳明经环绕唇口的部分，左右各有一条）。中于右侧的情况仿照此理。
This classification method divides the East, West, South, and North into four principal directions (Si Zheng), and further divides the Southeast, Southwest, Northeast, and Northwest into four intermediate directions (Si Wei), totaling eight directions. Each direction has its governing climate qi: South wind is hot, East wind is warm, West wind is dry, and North wind is cold; Southeast wind is both warm and hot, Southwest wind is both dry and hot, Northeast wind is both cold and warm, and Northwest wind is both cold and dry. This represents the normal state of climate (Ping Qi). If the wind is excessive, it is called "Thief Wind" (Zeifeng, pathogenic wind). If Thief Wind is mild, the invasion in humans is also mild; if Thief Wind is severe, the invasion in humans is also severe.
The warmth, heat, cold, and dryness of the winds from the eight directions are distinguished solely by the East-West and South-North axes, existing regardless of the season. This differs from the Six Qi (Liuqi, Wind, Cold, Summer-heat, Dampness, Dryness, Fire) where Spring warmth, Summer heat, Autumn dryness, and Winter cold each govern a specific season.
Wei Qi (Defensive Qi) warms and nourishes the形体 (body form). As stated in the *Huangdi Neijing* (Yellow Emperor's Inner Canon), it "guards the exterior to maintain solidity"; as stated in the *Nan Jing* (Classic of Difficult Issues), it is the "Divine Spirit guarding against pathogens." When Wei Qi is solid and dense, various pathogens cannot invade; if there is even a slight gap, pathogens will attack. If the gap is in the head, the face is struck, resulting only in deviation of the mouth and eyes, while the hands and feet remain unharmed. If the gap is in the meridians of the hands, the arms are struck, resulting only in the inability to raise the wrists and arms, while the head and feet remain unharmed. If the gap is in the meridians of the feet, the hip joint is struck, resulting only in slow and heavy gait, while the head and hands remain unharmed. If the gap is on the left, the left side is affected and the right is unharmed; if the gap is on the right, the right side is affected and the left is unharmed.
If the pathogen strikes the Foot Shaoyin Kidney Meridian, the tongue becomes dry and speech is slurred (because the Shaoyin meridian winds around the root of the tongue); if it strikes the Hand Jueyin Pericardium Meridian, mental fatigue and frequent forgetfulness occur (because the Hand Jueyin Pericardium acts on behalf of the Heart Monarch); if it strikes the Hand Shaoyang Sanjiao (Triple Burner) Meridian, Sanjiao function becomes obstructed leading to frequent hiccups or choking sensations, and constipation occurs; if it strikes the Foot Taiyang Bladder Meridian, the bladder fails to clear turbidity, leading to cloudy urine, and even urinary retention (Longbi, difficulty or impossibility of urination) where urine cannot be expelled. This is because the Qi transformation of the bladder relies entirely on the permeating and draining action of Wei Qi. When Wei Qi is attacked by pathogenic wind and cannot perform this draining function, retention results. Such symptoms are too numerous to list; they all depend on the location of the gap where the pathogen enters. The *Huangdi Neijing* states: "Wherever pathogenic qi gathers, Zheng Qi (Upright Qi) must be deficient." This is analogous to chopping wood: an axe does not easily enter hard wood, but penetrates soft, brittle wood easily. Thus, this type of disease mostly occurs in people after middle age, because their Wei Qi has somewhat declined. In young and vigorous people, one in a hundred might suffer from it, because their Wei Qi is robust. Later generations, misunderstanding the meaning of Wei Qi, proposed the theory of "Left Blood, Right Qi," which is far off the mark. Others claim that blood deficiency generates internal wind, which is also not quite accurate. It should be known that the generation of internal wind is due to the deficiency of Wei Qi creating gaps, just as wind arises in empty valleys. It is not due to blood deficiency. Deficiency creates gaps, allowing pathogenic wind to enter; hence it is called "internal wind inducing external wind." Wei Qi originates from the Lower Jiao and is the root of wind generation, which is what the *Huangdi Neijing* refers to as the "Moving Qi between the Kidneys" (Shenjian Dongqi). The opening/closing, waking/sleeping, and entering/exiting of Wei Qi are distributed left and right. At the beginning of human formation, when the fetus first takes shape, its form resembles two shells, i.e., the two kidneys, wherein Wei Qi resides. Therefore, its movement during opening/closing and waking/sleeping must also be distributed left and right. This is a credible truth of inner physiology, merely unrecognized by mediocre physicians.
The root of the Moving Qi is indeed Kidney Qi, but it is specifically called "Moving Qi between the Kidneys" because it is the master of perception and movement, hence the addition of the character "Move" to denote it. If the Wei Qi on both sides is balanced, perception and movement are naturally crisp, healthy, and sharp. If the Wei Qi on one side is healthy while the other is diseased, perception and movement will inevitably fail to be as crisp, healthy, and sharp as usual. As the saying goes: "Many hands make light work, but one person struggles alone." This serves as a good analogy.
When wind strikes the left, the disease is on the left; when it strikes the right, the disease is on the right. However, deviation of the mouth corner is different: when striking the left, the mouth corner deviates to the right; when striking the right, the mouth corner deviates to the left. The reason is that when the left Wei Qi ceases to function, the meridians on the left become flaccid and relaxed, while the Wei Qi on the right functions exclusively, causing the meridians on the right to contract and spasm, thus pulling the mouth corner to the right (the meridians at the mouth corner are part of the Yangming Meridian encircling the lips, with one on each side). The case of striking the right follows this logic.